Workers at the Vermont Health Connect call center in Burlington talk to customers Tuesday. It was the official startup date for Vermont Health Connect.

MONTPELIER — State officials are hailing Tuesday’s launch of an online health insurance marketplace as a success, but opponents were quick to denounce the new system as the online portal immediately experienced technical issues.

Tuesday marked the debut of Vermont Health Connect, the state’s version of the online health insurance exchanges required under the federal Affordable Care Act, widely referred to as Obamacare.

Starting Jan. 1, individuals and small businesses with fewer than 50 employees in Vermont will be required to buy health insurance on the exchange. It is expected to serve about 100,000 people.

The marketplace allows consumers to compare plans and prices offered by Blue Cross Blue Shield of Vermont and MVP Health Care and then enroll. It also allows consumers to see if they are eligible for state subsidies and federal tax credits to help cover the cost of insurance.

But the much-touted launch was far from smooth. The website was slow to load — or failed to load — for many people. Officials said heavy traffic on the site was to blame.

As of 4 p.m. about 8,500 unique visitors had been to the site. About 600 people had contacted a call center that also launched Tuesday, according to Emily Yahr, a Vermont Health Connect spokeswoman.

Technical issues were expected as the state implements the sweeping change in health care, officials said.

“We certainly know that it’s an issue. We’re aware of it and we’re working on it, and we’ll have it resolved as soon as we can,” said Robin Lunge, the Shumlin administration’s director of health care reform.

“We certainly anticipated that there would be some bumps in the road,” she said, “so we were not surprised that there were some challenges.”

A technical team was working Tuesday to address issues with the site and improve its performance, she said.

“My understanding is that there’s a process that IT goes through when they’re looking at website slowness,” Lunge said. “They have been working through their step-by-step process to eliminate issues. They’ve eliminated a number of issues, so they’re narrowing it down.”

Susan Klein, executive director of the Mad River Valley Chamber of Commerce and one of 250 exchange “navigators” who will help Vermonters understand and use the new system, said her attempts to access the site Tuesday morning were unsuccessful. The site loaded in the afternoon, but she said she was still unable to register.

“My first task was to try to register myself as a navigator. I was not able to get that far,” she said.

The site seemed to be overloaded, Klein said.

“I think there’s quite a traffic jam. Everybody is trying to get through the same door at the same time,” she said.

Still, Vermonters “have plenty of time” to access the exchange and choose a health care plan that suits them during the open enrollment period, Klein said. Most Vermonters are not yet inclined to do so anyway, she said.

“I think people are not quite in a panic to get enrolled at this point,” Klein said.

Vermont is one of 14 states that designed its own online marketplace. Most states opted to let the federal government build and implement theirs. Democratic Gov. Peter Shumlin was quick to embrace federal health care reform — and the $172 million in funding provided by the Obama administration to create the exchange.

Mark Larson. commissioner of the Vermont Department of Health Access, touted the benefits the exchange will provide Vermonters.

“I am proud of our staff for their hard work to date, and I am confident that commitment will continue as Vermonters access the marketplace to make smart health coverage decisions over the course of the six month open-enrollment period,” Larson said in a statement.

“Today marks a crucial first step in Vermont’s move to provide quality coverage, help small businesses and Vermonters afford insurance, and control the staggering increases in health care costs,” he added.

States across the country also experienced technical glitches as their sites launched. Even the federal site, for the 36 states using the exchange set up by the federal government, was similarly hampered. President Barack Obama said during remarks Tuesday afternoon in the Rose Garden that more than 1 million people had visited the site by 7 a.m.

“We think that today is an important milestone and is a success,” she said.

More than 330 Vermonters registered Tuesday, according to Lunge. Others were simply reviewing their options, she said. The system is expected to allow consumers to begin paying for insurance plans Nov. 1.

“We definitely have had folks create accounts. We know folks have been spending time on the website shopping and looking for plans as well,” she said.

But opponents of health care reform seized on the glitches as a sign that Obama’s signature achievement was failing.

Darcie Johnston, whose advocacy group Vermonters for Health Care Freedom has been declaring for some time that the exchange would not be ready for launch, said Shumlin and other officials have not been up front with Vermonters about the exchange’s limitations.

“Gov. Shumlin should tell the truth and tell the truth fast,” Johnston said.

The system’s failures Tuesday raise significant questions about whether the exchange will be able to begin offering coverage as planned in January, she said.

“I don’t see the success, or anywhere close to it, or the confidence in the system, that is going to allow people to have coverage come Jan. 1,” Johnston said.

“At some point people have to pay for health care. The governor has now said Nov. 1. OK, they’ll do what they do between now and Nov. 1 and we’ll see if they can pay. My bet is they can’t.”